antlr-calculator

This calculator is using the ANTLR4 JavaScript target to calculate results from formulas that are passed in as string. Both JavaScript and TypeScript is supported.

It's a Visual Studio solution project and requires TypeScript >= 2.0.2 to run. Output is generated by doing first npm install and then running the npm run build command in the project directory (no Visual Studio required). The JavaScript bundle.js is gzipped just a bit over 50 kb.

Whenever a calculation is performed, a CalculationResult is returned with the following properties:

Property	Type
isValid	boolean	true if the formula could be parsed and calculated, else false
errorPosition	number	Position of the offending symbol in the line, 0 based index, for invalid results, else null
errorMessage	string	ANTLR error message for invalid formulas, else null
result	number	NaN for invalid formulas, else the actual result

Unit tests are performed using Chutzpah (via console in CI and with the Visual Studio extension while developing).

Since this is mostly a learning project, expect bugs😉

You can check out the live demo here!

Installation

Clone this repository or just go with npm install antlr-calculator.

JavaScript

Just reference dist/bundle.js and the global variable antlrCalc is available.

var result = antlrCalc.Calculator.calculate('4*5');
console.log(JSON.stringify(result, null, 2));

//  {
//    "isValid": true,
//    "errorPosition": null,
//    "errorMessage": null,
//    "result": 20
//  }

TypeScript

Import the Calculator class and use the static calculate(formula: string) method to evaluate formulas.

import { Calculator } from 'antlr-calculator';

var result = Calculator.calculate('4*5');
console.log(JSON.stringify(result, null, 2));

//  {
//    "isValid": true,
//    "errorPosition": null,
//    "errorMessage": null,
//    "result": 20
//  }

Cannot resolve module 'fs' error

The FileStream class in the antlr4 library has a call to require('fs') if the current environment is detected to be node.js. You might get errors indicating that the fs module cannot be resolved. When running in the browser, it's safe to ignore this module.

Ignore fs module in webpack

Add the following to your webpack.config:

node: {
  fs: 'empty'
}

Supported functions

Expression
FLOOR expression	Round down to zero accuracy
CEIL expression	Round up to zero accuracy
ABS expression	Absolute value
ROUNDK '(' expression ';' expression ')'	Round expr_1 with expr_2 accuracy
ROUND expression	Round with zero accuracy
TRUNC expression	Trim decimal digits
SIN expression	Sinus
COS expression	Cosinus
TAN expression	Tangens
COT expression	Cotangens
SINH expression	Sinus Hypererbolicus
COSH expression	Cosinus Hyperbolicus
TANH expression	Tangens Hyperbolicus
ARCSIN expression	Inverse Sinus
ARCCOS expression	Inverse Cosinus
ARCTAN expression	Inverse Tangens
ARCTAN2 '(' expression ';' expression ')'	Atan2
ARCCOT expression	Inverse Cotangens
EXP expression	e ^ expr
LN expression	Logarithm to e
EEX expression	10 ^ expr
LOG expression	Logarithm to 10
RAD expression	Angle to radians (360° base)
DEG expression	Radians to angle (360° base)
SQRT expression	Square root
SQR expression	Square product
`expression op = ('^'	'**') expression`
`expression (MOD	'%' ) expression`
expression DIV expression	Whole part of division rest
`expression op = ('~'	'//') expression`
`expression op = ('*'	'/') expression`
`expression op = ('+'	'-') expression`
NUMBER	Single integer or float number
'(' expression ')'	Expression within parentheses
PI '()'?	Mathematical constant pi = 3,141593
expression E+ expression	Exponent, e.g. 10e+43
expression E- expression	Inverted Exponent, e.g. 10e-43
EULER	Mathematical constant e = 2,718282
'-' expression	Unary minus sign (negative numbers)
'+' expression	Unary plus sign (positive numbers)

expression may be any expression as functions can be nested. Example: DEG(2*PI) or LOG(10^3).

Formulas can be case invariant, e.g. SIN, sin and siN are all considered the same.

Comments in Formulas

Comments in Formulas are supported by encapsulating them either in /*...*/, '...' or "..." quote styles. Examples:

4/*Length*/*3/*Width*/ resolves to 12

4'Length'*3'Width' resolves to 12

4"Length"*3"Width" resolves to 12

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MIT License